[FLINK-34719][streaming] Fix unstable test StreamRecordTest.testWithTimestamp above jdk8

[Jiabao-Sun]

What is the purpose of the change

[FLINK-34719][streaming] Fix unstable test StreamRecordTest.testWithTimestamp above jdk8

Brief change log

Fix unstable test StreamRecordTest.testWithTimestamp above jdk8

Verifying this change

use jdk11

mvn test -Dtest=oorg.apache.flink.streaming.runtime.streamrecord.StreamRecordTest

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
• The serializers: (no)
• The runtime per-record code paths (performance sensitive): (no)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (no)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (no)
• If yes, how is the feature documented? (not documented)

[Jiabao-Sun]

Hi @RyanSkraba.
Would you help review this PR when you have time?
Thanks.

[flinkbot]

CI report:

• 113c8cf Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run azure re-run the last Azure build

[RyanSkraba]

LGTM, thanks for the quick fix! I think that it's OK not to test the message in this case -- the fact that it is a ClassCastException is already enough!